WIP1 dephosphorylation of p27Kip1 Serine 140 destabilizes p27Kip1 and reverses anti-proliferative effects of ATM phosphorylation
WIP1 dephosphorylation of p27Kip1 Serine 140 destabilizes p27Kip1 and reverses anti-proliferative effects of ATM phosphorylation
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DOI：
10.1080/15384101.2020.1717025
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发表时间：
2020-01-23
期刊：
影响因子：
4.3
通讯作者：
Donehower, Lawrence A.
中科院分区：
文献类型：
--
作者：
Choi, Byung-Kwon;Fujiwara, Kenichiro;Donehower, Lawrence A.
ATM 和 ATR 等磷酸肌醇 3 激酶样激酶 (PIKK) 在启动细胞 DNA 损伤反应 (DDR) 中发挥着关键作用。 ATM 的一个关键靶标是细胞周期蛋白依赖性激酶抑制剂 p27 (Kip1)，它可促进 G1 期停滞。 ATM 部分通过 p27(Kip1) 在丝氨酸 140 处的磷酸化来激活 p27(Kip1) 诱导的停滞。在这里，我们表明该位点被 PPM1D 基因编码的 2C 型丝氨酸/苏氨酸磷酸酶 WIP1（野生型 p53 诱导的磷酸酶-1）去磷酸化。 WIP1 已被证明可以使 DDR 蛋白中的许多 ATM 靶位点去磷酸化，并且其过度表达和/或突变通常与肿瘤发生有关。我们证明，野生型而非磷酸酶死亡 WIP1 在体外和细胞内都能有效地使 p27(Kip1) Ser140 去磷酸化，并且这种去磷酸化对 WIP1 特异性抑制剂 GSK 2830371 敏感。野生型 WIP1 表达的增加会降低 p27(Kip1) 的稳定性，而类似量的磷酸酶死亡 WIP1 表达增加对 p27(Kip1) 蛋白没有影响稳定性。相对于 p27 的 S140A（组成型非磷酸化）形式，野生型 p27(Kip1) 的过表达会降低细胞增殖和集落形成能力。因此，WIP1 在 ATM 激活后 p27(Kip1) 活性的稳态调节中发挥着重要作用。
The phosphoinositide-3-kinase like kinases (PIKK) such as ATM and ATR play a key role in initiating the cellular DNA damage response (DDR). One key ATM target is the cyclin-dependent kinase inhibitor p27(Kip1) that promotes G1 arrest. ATM activates p27(Kip1)-induced arrest in part through phosphorylation of p27(Kip1) at Serine 140. Here we show that this site is dephosphorylated by the type 2C serine/threonine phosphatase, WIP1 (Wildtype p53-Induced Phosphatase-1), encoded by the PPM1D gene. WIP1 has been shown to dephosphorylate numerous ATM target sites in DDR proteins, and its overexpression and/or mutation has often been associated with oncogenesis. We demonstrate that wildtype, but not phosphatase-dead WIP1, efficiently dephosphorylates p27(Kip1) Ser140 both in vitro and in cells and that this dephosphorylation is sensitive to the WIP1-specific inhibitor GSK 2830371. Increased expression of wildtype WIP1 reduces stability of p27(Kip1) while increased expression of similar amounts of phosphatase-dead WIP1 has no effect on p27(Kip1) protein stability. Overexpression of wildtype p27(Kip1) reduces cell proliferation and colony forming capability relative to the S140A (constitutively non-phosphorylated) form of p27. Thus, WIP1 plays a significant role in homeostatic modulation of p27(Kip1) activity following activation by ATM.